1. Field of the Invention
This invention relates to cell culture carriers and a method for the culture of cells, particularly to the cell culture carriers suitable for use in high-density culture of anchorage-dependent cells and the method for the cell culture by using said carriers.
2. Description of the Prior Art
There are many known methods for the cell culture in large quantity and in high-density, such as those using microcapsule, hollow fiber, ceramic carriers, microcarriers and glass beads.
With the recent progress in methodology of the cell culture, however, it has become necessary to develop cell culture carriers and methods for the cell culture which allow the cell culture in much higher density than before. Since carriers such as microcarriers and glass beads, in which cells can anchor or adhere only to the surface of the carriers, have a low surface area per a unit of volume (hereinafter referred to as "a S/V value"), they cannot be advantageously used in the high-density cell culture.
For the purpose of enabling such high-density cell culture, there have been proposed a few kinds of cell culture carriers whose inner surface may also serve as the surface to which cells can adhere, i.e., as "an anchorage area."
Japanese Patent Application Laying Open (KOKAI) No. 502936/87 and Bio/technology, Vol. 5, pp. 835-837, 1987 (Verax Corporation) disclose spherical carriers made of three-dimensionally woven collagen fiber, which, however, cannot be subjected to sterilization by an autoclave.
Japanese Patent Application Laying Open (KOKAI) No. 169837/87 and Bio/technology, Vol. 4, pp. 989-990 (1987) refer to possibility of the high-density cell culture by using porous gelatin carriers. The porous gelatin carriers may be sterilized by a autoclave, but even highly anchorage-dependent cells can hardly adhere to them, requiring a special adhering technique.
G. A. Pkhakadze reports in Ukr. Biokhim. Zh., Vol.51, 4. pp. 355-362 (1979) that rat fibroblasts can be cultured with polyurethane carriers.
Japanese Patent Application Laying Open (KOKAI) No. 215386/87 discloses possibility of the high-density cell culture by using polyurethane foam carriers. However, cells can hardly adhere to such carriers. Even if they are attached to said carriers, they proliferate very slowly and detach therefrom very easily. Furthermore, protein or virus secreted from the attached cells will likely be adsorbed by the carriers. Watabe et al. reports that materials eluted from polyurethane deteriorate the development of culture cells (Reports of the institute for medical and dental engineering, Tokyo Medical and Dental University, Vol. 10, pp. 69-75 (1976)).
The inventors of the present application have previously disclosed, in Japanese Patent Applications Laying Open (KOKAI) No. 71173/88, No. 226282/88 and 10979/89, cell microcarriers consisting of water-insoluble polymer particles constituted by (meth)acrylic acid ester and having a positively chargeable chemical moiety or protein, which is chemically bound to their surface. However, since the anchorage area of the particles with a low S/V value was restricted only to their outer surface, the above cell microcarriers could not sufficiently provide the high-density cell culture, as mentioned above.
Accordingly, there has been a great demand for cell carriers which can attach and grow cells well and can be sterilized by an autoclave.